Plasmonic Perfect Absorber Research Articles

Design and performance of a dual-band plasmonic perfect absorber for infrared refractive index sensing

In this study, we introduce what we believe is an innovative design for a plasmonic perfect absorber (PPA) that is based on half-cut disk resonator metamaterials. This design exhibits remarkable stability and versatility, demonstrating effective functionality across a wide range of incident angles for both transverse electric (TE) and transverse magnetic (TM) polarization. The distinct operational characteristics of the PPA are highlighted by the presence of two corresponding absorption peaks at wavelengths of 870 and 1599 nm, where it achieves outstanding maximum absorption rates of 98.99% and 97.5%, respectively. The design’s ultra-narrow resonance peaks are indicative of its high-quality factors, which are vital for enhancing sensitivity in plasmonic sensory applications. This characteristic renders our PPA an exceptional candidate for refractive index (RI) sensing, where precision is critical. The dual-band perfect absorber (PA)-based sensor demonstrates significant RI sensitivity, with values approximately equal to 365 nm/RIU at the first absorption peak and 733 nm/RIU at the second. Our findings elucidate the exceptional potential inherent in this novel dual-band perfect absorber design. The versatility and efficiency across varied applications not only contribute to the existing body of knowledge but also pave the way for future advancements in plasmonic sensor technologies and metamaterial research.

A Tunable Plasmonic Perfect Absorber based on Graphene and Two Metal-insulator Substructures

Background: In recent decades, numerous researchers have been keenly interested in plasmonic absorbers due to their efficiency in a variety of applications such as solar cells. This is because the surface plasmons formed at the interface between metal and insulators interact strongly with light, thereby augmenting electromagnetic (EM) waves. In most cases, plasmonic absorbers featuring metal-insulated-metal structure (MIM) are favored for their robust absorption rates, straightforward fabrication process, minuscule size, and portability. Methods: This paper proposes a tunable plasmonic perfect absorber (PPA) based on graphene and two metal-insulator substructure within the 28-60 μm wavelength range. This device is simulated by 3D finite element analysis using CST software. Also, in our proposed structure, instead of using a single micro-blade, two micro-blades are arranged opposite of each other in the absorber structure through which the electric field is locally strengthened and a sharper resonance peak with greater amplitude is obtained. Results: Simulation results demonstrate that a resonance peak is observable in the absorption spectrum of the structure and that this peak can be shifted between 30μm and 40μm by applying a gate bias voltage to the graphene nanolayer without modification of the structure's dimensions. Conclusion: The features of this absorber make it suitable for sensor applications, which will be further explored in future research. We also investigated the influence of dimensions on absorption to take into account the allowable tolerances and sensitivities associated with its fabrication. Furthermore, we proposed a structure that can enhance absorber performance in the future.

Design nano cluster high Q-factor perfect plasmonic absorber for bacteria detection in the optical range

Plasmonic nanostructures enable strong light absorption at the nanometer scale, making them highly attractive for a variety of applications including sensing, imaging, and spectroscopy. In this work, we propose and simulate a dual-band plasmonic absorber based on a Pentamer and split ring resonator (SRR) hybrid structure. The absorber operates at terahertz frequencies of 209 and 229 THz, corresponding to free-space wavelengths of 1310 nm and 1430 nm. At the lower frequency band, the absorber provides perfect absorption up to 100 %, while at the higher band, the absorption is 95 %. The high absorption selectivity at the two target bands is enabled by the hybrid heptamer-SRR design. The central Pentamer consists of a central nanodisk surrounded by four peripheral nanodisks with precise dimensions and spacing. This Pentamer provides a dual-band response tuned to the desired frequencies. To further enhance the quality factor and absorption, the Pentamer is encircled by an SRR designed to boost the Q-factor. At 229 THz, the SRR pushes the quality factor to around 635, significantly higher than typical plasmonic absorbers. The final optimized design enables strong absorption together with high Q-factor and frequency selectivity. It exhibits sensitivity around 450 nm/RIU and a Figure of Merit of 227 RIU−1. The full-wave simulation is used for designing the absorber in CST Microwave Studio to optimize the dimensions for maximum dual-band absorption for biosensing applications. This absorber can be realistically fabricated for terahertz sensing applications such as detecting bacteria as studied.

A plasmonic terahertz perfect absorber based on L-shaped graphene patches and gold rods

A plasmonic terahertz perfect absorber based on L-shaped graphene patches and gold rods

THz time-domain spectroscopy modulated with semiconductor plasmonic perfect absorbers.

Terahertz time-domain spectroscopy (THz-TDS) at room temperature and standard atmosphere pressure remains so far the backbone of THz photonics in numerous applications for civil and defense levels. Plasmonic microstructures and metasurfaces are particularly promising for improving THz spectroscopy techniques and developing biomedical and environmental sensors. Highly doped semiconductors are suitable for replacing the traditional plasmonic noble metals in the THz range. We present a perfect absorber structure based on semiconductor III-Sb epitaxial layers. The insulator layer is GaSb while the metal-like layers are Si doped InAsSb (∼5·1019 cm-3). The doping is optically measured in the IR with polaritonic effects at the Brewster angle mode. Theoretically, the surface can be engineered in frequency selective absorption array areas of an extensive THz region from 1.0 to 6.0 THz. The technological process is based on a single resist layer used as hard mask in dry etching defined by electron beam lithography. A wide 1350 GHz cumulative bandwidth experimental absorption is measured in THz-TDS between 1.0 and 2.5 THz, only limited by the air-exposed reflectance configuration. These results pave the way to implement finely tuned selective surfaces based on semiconductors to enhance light-matter interaction in the THz region.

Mirror‐Coupled Plasmonic Bound States in the Continuum for Tunable Perfect Absorption

AbstractTailoring critical light‐matter coupling is a fundamental challenge of nanophotonics, impacting fields from higher harmonic generation and energy conversion to surface‐enhanced spectroscopy. Plasmonic perfect absorbers (PAs), where resonant antennas couple to their mirror images in adjacent metal films, excel at obtaining different coupling regimes by tuning the antenna‐film gap size. However, practical PA applications require constant gap size, making it impossible to maintain critical coupling beyond singular wavelengths. Here, a new approach for plasmonic PAs is introduced by combining mirror‐coupled resonances with the unique loss engineering capabilities of plasmonic quasi‐bound states in the continuum. This novel combination allows to tailor the light–matter interaction within the under‐coupling, over‐coupling, and critical coupling regimes using flexible tuning knobs including asymmetry parameter, dielectric gap, and geometrical scaling factor. The study demonstrates a pixelated PA metasurface with optimal absorption over a broad range of mid‐infrared wavenumbers (950–2000 cm−1) using only a single gap size and applies it for multispectral surface‐enhanced molecular spectroscopy. Moreover, the asymmetry parameter enables convenient adjustment of the quality factor and resonance amplitude. This concept expands the capabilities and flexibility of traditional gap‐tuned PAs, opening new perspectives for miniaturized sensing platforms towards on‐chip and in situ detection.

Towards fiber-coupled plasmonic perfect absorber superconducting nanowire photodetectors for the near- and mid-infrared

Modern photon-based technologies are in need for fast detectors with the ability to detect photons in the near- and mid-IR efficiently. Superconducting nanowire photon detectors, which use the resistivity change upon photon incidence caused by a state transition from their superconducting to normal conducting phase, are state-of-the-art detectors. However, detectors usually suffer from low efficiency in the IR, due to their low intrinsic absorption in this spectral range. To enhance the detection efficiency, we use a plasmonic perfect absorber geometry, which utilizes a localized surface plasmon resonance and a spacer/mirror combination. We present superconducting niobium plasmonic perfect absorber nanostructures, featuring near-unity absorption, tailorable up to wavelengths of 4 µm. Further, we confirm the working principle of the plasmonic perfect absorber for wavelengths in the near-IR, which manifests itself as a polarization-dependent detector response. Finally, we demonstrate an approach of coupling the detector directly to a fiber. This might also enable ultrasensitive sensing application in the near- and mid-IR in the future.

GST plasmonic gap structure investigation as a switch and sensor.

In this paper, a plasmonic perfect absorber that consists of a gold rectangular bar with three gaps is investigated as a switch and sensor in the near-infrared region. Phase change material germanium-antimony-tellurium (GST) is utilized in two gaps to perform the switching capability with a high extinction ratio of 18.49dB. In addition, the sensing performance of the structure for detection of a solution of glucose in water and diagnosis of different cancer cells is studied. The best sensitivity of 1504nm/RIU is obtained for detection of the PC12 cancer cell, and the figure of merit of the structure is around 17R I U -1.

Plasmonic Perfect Absorber Based on Graphene and Its Sensing Application

Plasmonic Perfect Absorber Based on Graphene and Its Sensing Application

Developing perfect Plasmonic absorber as an optical surface based on pyramidal element with Nobel metal and composite

In the field of optical device design, some structures, such as absorbers, can be quite challenging to fabricate due to their complexity. In such cases, composite materials can offer a viable solution for developing and manufacturing these intricate structures. One type of composite, namely DNA-metal, can be employed to address this challenge. This study comprises three main sections: the design of a pyramidal element as a dual-band Plasmonic absorber, operating at 1790 nm (with 94.4% absorption) and 2519 nm (with 99.9% absorption); the utilization of a new material based on the Drude model to replace a complex initial model; and the incorporation of the basic structure as an optical sensor. Additionally, a perfect absorber is designed for 2455 nm, achieving a remarkable 99.9% absorption and a high Q-factor. The investigation of this element aims to elucidate its role in the absorber and the interaction between layers to achieve optimal absorption. The finite integrated technique (FIT) is employed for simulating this absorber. Finally, the absorber is utilized for optical sensing, specifically based on redshift, by evaluating sensitivity and the figure of merit (FOM). The interaction between the layers of the absorber element is leveraged to achieve a dual-band response and increase the effective length of the nanostructure.

Long-wave infrared photothermoelectric detectors with ultrahigh polarization sensitivity

Filter-free miniaturized polarization-sensitive photodetectors have important applications in the next-generation on-chip polarimeters. However, their polarization sensitivity is thus far limited by the intrinsic low diattenuation and inefficient photon-to-electron conversion. Here, we implement experimentally a miniaturized detector based on one-dimensional tellurium nanoribbon, which can significantly improve the photothermoelectric responses by translating the polarization-sensitive absorption into a large temperature gradient together with the finite-size effect of a perfect plasmonic absorber. Our devices exhibit a zero-bias responsivity of 410 V/W and an ultrahigh polarization ratio (2.5 × 104), as well as a peak polarization angle sensitivity of 7.10 V/W•degree, which is one order of magnitude higher than those reported in the literature. Full linear polarimetry detection is also achieved with the proposed device in a simple geometrical configuration. Polarization-coded communication and optical strain measurement are demonstrated showing the great potential of the proposed devices. Our work presents a feasible solution for miniaturized room-temperature infrared photodetectors with ultrahigh polarization sensitivity.

Exploring the resonance absorption of subwavelength-patterned epitaxial-grown group-IV semiconductor composite structures.

We experimentally and theoretically demonstrate a mid-infrared perfect absorber with all group-IV epitaxial layered composite structures. The multispectral narrowband strong absorption (>98%) is attributed to the combined effects of the asymmetric Fabry-Perot (FP) interference and the plasmonic resonance in the subwavelength-patterned metal-dielectric-metal (MDM) stack. The spectral position and intensity of the absorption resonance were analyzed by reflection and transmission. While a localized plasmon resonance in the dual-metal region was found to be modulated by both the horizontal (ribbon width) and vertical (spacer layer thickness) profile, the asymmetric FP modes were modulated merely by the vertical geometric parameters. Semi-empirical calculations show strong coupling between modes with a large Rabi-splitting energy reaching 46% of the mean energy of the plasmonic mode under proper horizontal profile. A wavelength-adjustable all-group-IV-semiconductor plasmonic perfect absorber has potential for photonic-electronic integration.

Dual-band plasmonic perfect absorber for refractive index sensing from mid- to near infrared region

A plasmonic perfect absorber (PA) utilizes high absorption of incident radiation and near-field enhancement which is so advantageous for many applications such as solar cell, infrared (IR) spectroscopy, and refractive index (RI) sensitivity. In this study, the numerically presented PA system has resonances from mid-infrared (MIR) to near-infrared (NIR) regions for different periodicities at 2.0, 2.4, and 2.8 µm. A fine-tuning mechanism is obtained to control the spectral response of PA through the geometrical parameters. Dual-band plasmonic resonances have nearly 98% absorption. Near-field intensity distributions are shown with the enhancement factor of 103 at the resonance frequencies. Refractive index sensitivity is also analyzed by embedding PA in different cladding mediums to show the sensing performance. Relationship between resonance wavelength and refractive index of the medium is observed for all resonant modes. The highest sensitivity value is 2382.48 nm/RIU and the figure of merit reaches as high as 28.29 RIU−1.

Design of a triple-band black phosphorus-based perfect absorber and full-wave analysis using the semi-analytical method of lines

A novel triple-band perfect plasmonic absorber that operates in the infrared regime was designed in this study. This absorber has a periodic multilayered black phosphorus (BP)/dielectric structure mounted on an Ag mirror with three distinct absorption peaks located at 6.44 µm, 10.09 µm, and 17.46 µm, and with near perfect absorption efficiencies of 96.72%, 97.17%, and 95.62%, respectively. The absorption performance of the designed structure can be tuned independently for each of the resonance bands by controlling the corresponding Fermi level of the BP-nanoribbons. Moreover, we demonstrated that the operation of the proposed absorber is independent of the incident angles in the angular range from normal to ± 50°. The semi-analytical method of lines was extended to conduct full-wave analysis of the proposed absorber. The semi-analytical nature of this method greatly reduces the computational time required and memory consumption compared with fully numerical methods. Direct comparisons with the results obtained by using the finite difference time domain method demonstrated their full consistency.

Plasmonic Refractive Index and Temperature Sensor Based on Graphene and LiNbO3.

A high-efficiency dual-purpose plasmonic perfect absorber sensor based on LiNbO3 and graphene layers was investigated in this paper for the refractive index and thermal sensing. The sensor design was kept simple for easy fabrication, comprising a LiNbO3 substrate with a quartz layer, thin layer of graphene, four gold nanorods, and a nanocavity in each unit cell. The nanocavity is located in the middle of the cell to facilitate the penetration of EM energy to the subsurface layers. The proposed sensor design achieved an output response of 99.9% reflection, which was easy to detect without having any specialized conditions for operability. The performance of the device was numerically investigated for the biomedical refractive index range of 1.33 to 1.40, yielding a sensitivity value of 981 nm/RIU with a figure-of-merit of 61.31 RIU−1. By including an additional polydimethylsiloxane polymer functional layer on the top, the device was also tested as a thermal sensor, which yielded a sensitivity level of −0.23 nm/°C.

Tunable infrared high absorbing polarization independent niobium nitride plasmonic perfect absorber nanowire photodetectors

The recent development of photon-based technologies such as quantum cryptography and quantum computing requires high fidelity and fast photodetectors, as well as the ability to detect single photons. One possibility to achieve these goals are superconducting nanowire single photon detectors, utilizing the superconducting-to-normal conducting phase transition. To achieve the required high efficiency, we use resonant plasmonic perfect absorber effects, reaching over 90% polarization-independent absorbance at our target wavelength of 1140 nm. Moreover, the target wavelength can be easily tuned by adjusting the geometry of our detectors. Furthermore, the high absorbance is maintained at oblique incidence, due to the plasmonic perfect absorber principle, and small active areas can be achieved by the high resonant absorption cross-section of plasmonic resonances. We fabricated different tunable, polarization independent plasmonic perfect absorber superconducting nanowire photodetectors and proved their high absorbance and polarization independent response in the wavelength regime around 1140 nm.

All-metal plasmonic metasurface at NIR wavelengths for optical absorption manipulation and refractive index sensing

All-metal near-infrared (NIR) plasmonic perfect absorbers made of subwavelength rings and ring-discs on a flat metal layer are proposed and numerically investigated using FDTD solver. A simple design concept is applied to achieve multi-resonant absorption. Ring inner diameter and outer diameter are set equal to p-200 nm and p-100 nm, respectively, where, p = period of the structure, and a disc of appropriate size is co-axially introduced at the centre of the gold ring to controllably achieve 100% absorption. Passive controlling of the disc size changes single absorption mode to dual absorption modes. Further, multiple resonant absorptions at tunable NIR wavelengths are achieved by embedding the structures into a dielectric medium of high dielectric constant. The proposed structure is seen to be highly sensitive to the surrounding medium that can measure refracting index with high sensitivity > 850 nm/RIU. The robust design of the proposed structure is suitable for optoelectronic devices.

Ultra-sensitive narrow-band plasmonic perfect absorber for sensing applications

Plasmonic nanostructure-based sensors have a broad range of applications in food assessment, hazardous gas monitoring, medical diagnosis, and vapor sensing. However, it is still challenging to establish a high performance plasmonic sensing platform that simultaneously provides high refractive index sensitivity and high figure of merit values. Based on simulations using the finite element method, we engineered an ultra-sensitive all-metal plasmonic perfect absorber (a-MPPA) for sensing applications. The proposed a-MPPA structure is based on closely spaced silver (Ag) nanocones over an Ag thin film and it exhibits ultra-sharp spectral absorption with robust hot spots of electric and magnetic fields. The high optical absorption and localized giant field enhancement depend on the structural configuration of the platform. We observed that the absorbance of the optimized structure exceeded 99%, with an ultra-narrow plasmonic peak (4.3 nm), thereby suggesting that the proposed nanostructure is a good candidate for sensing applications. The sensing performance of the a-MPPA platform was outstanding, with bulk sensitivity of 1006 nm/RIU, large figure of merit value of 233.9 RIU−1, and high quality factor of 233.4. Theoretical analyses based on Campbell’s model indicated that the a-MPPA platform is suitable for molecular detection, with a detection range extending to 50 nm. The proposed narrow-band perfect absorption plasmonic nanostructure has great potential for applications in sensing.

Graphene-Based Plasmonic Metamaterial Perfect Absorber for Biosensing Applications

Graphene as a mono-atomic sheet has recently grabbed attention as a material with enormous properties. It has also been examined for enhancing absorbance in the current plasmonic structure. This has led to an increment in the sensitivity of the plasmonic sensors. In this paper, we present theoretical investigation of the novel graphene-based plasmonic metamaterial perfect absorber for biosensing applications. The simulation study performs the analysis of the novel plasmonic metamaterial absorber structure by adding coatings of graphene sheets. Each sheet of graphene enhances absorbance of the structure. In this study, we demonstrate three layers of graphene sheets lead to perfect absorbance (100%) for multiple bands in the visible and near-infrared regions. Furthermore, we also computed the sensitivity of the graphene-based proposed structure by varying the refractive index (RI) of the sensing region from 1.33–1.36 with RI change of 0.01. Proposed fabrication steps for realization of the device are also discussed.

Plasmonic perfect absorber based on the ring hole and slot waveguide for sensing applications

A plasmonic perfect absorber based on the ring hole and slot waveguide in three different structures is proposed as a sensor and simulated using the three-dimensional finite-difference time-domain numerical method for perpendicular incidence of a plane wave light within 900 to 1900 nm wavelength range. The simulation results show that two resonance peaks emerged in the absorption spectrum of the devices. To investigate the sensing capability of this absorber, the ring holes and slot waveguides on the upper surface of the structures are filled with analytes with different refractive indices. It is observed that the resonance peaks are redshifted with increasing the refractive index of the analyte. The sensitivity of the first and second resonance peaks for structure 1 is 260.7 and 154.4 nm / RIU, respectively, for structure 2 are 303.4 and 102.7 nm / RIU, respectively, and for structure 3 are 261.9 and 103.2 nm / RIU, respectively, which indicates the good ability of the devices to detect analytes with refractive indices close to each other.